In-flight reconfigurable hybrid unmanned aerial vehicle

ABSTRACT

This disclosure is directed to an unmanned aerial vehicle (“UAV”) that transitions in-flight between vertical flight configuration and horizontal flight configuration by changing an orientation of the UAV by approximately ninety degrees. The UAV may include propulsion units that are coupled to a wing. The wing may include wing segments rotatably coupled together by pivots that rotate to position the propulsion units around a center of mass of the UAV when the fuselage is oriented perpendicular with the horizon. In this vertical flight configuration, the UAV may perform vertical flight or hover. During the vertical flight, the UAV may cause the wing to extend outward via the pivots such that the wing segments become positioned substantially parallel to one another and the wing resembles a conventional fixed wing. With the wing extended, the UAV assumes a horizontal flight configuration that provides upward lift generated from the wing.

BACKGROUND

Automated aerial vehicles, sometimes referred to as drones or unmannedaerial vehicles (UAVs), have become commonly used by hobbyists, somecommercial entities, and various government entities. Many of theseaerial vehicles are used for image capture, for example, by hobbyists;however, many other uses exist.

Aircraft are often designed for a specific type of flight. Fixed wingaircraft, which primarily rely on a wing for upward lift, typicallyinclude a propulsion system that is in fixed orientation and providesthrust in the single direction that, during horizontal flight, isapproximately parallel with the horizon. Aircraft that rely on rotorsfor propulsion, such as helicopters, quadcopters, and other rotorcraft,primarily rely on the rotors for upward lift and typically include apropulsion system that is in fixed orientation and provides thrust inthe single direction that, during flight, is approximately perpendicularwith the horizon. Some hybrid aircraft rely on both rotors and wings toprovide upward lift, depending on a mode of flight. A classic example isthe Boeing V-22 Osprey, which uses tilt-rotors that rotate relative tothe fuselage to enable transition from a rotor-lift-based mode of flightto a wing-lift-based mode of flight.

Unmanned aerial vehicles offer unique advantages and considerations ascompared to their counterpart manned aerial vehicles (e.g., typicalhelicopters and fixed wing aircraft). For example, unmanned aerialvehicles may be smaller in overall size and lightweight as compared totheir counterpart manned aerial vehicles. The size and thrust ratios ofpropulsion systems for unmanned aerial vehicles allow these aerialvehicles to perform maneuvers that may not be possible or may not bepractical for their counterpart manned aerial vehicles.

BRIEF DESCRIPTION OF THE DRAWINGS

The detailed description is described with reference to the accompanyingfigures. In the figures, the left-most digit(s) of a reference numberidentifies the figure in which the reference number first appears. Thesame reference numbers in different figures indicate similar oridentical items.

FIG. 1 is a pictorial flow diagram showing an illustrative process oftransitioning between a vertical flight configuration and a horizontalflight configuration by an unmanned aerial vehicle (UAV).

FIGS. 2A-2C show an UAV, which includes an in-flight reconfigurable wingstructure, in a horizontal flight configuration. FIG. 2A is an isometricview of the UAV. FIG. 2B is a side elevation view of the UAV. FIG. 2C isa top view of the UAV.

FIGS. 3A-3C show the UAV from FIG. 2A in a vertical flightconfiguration. FIG. 3A is an isometric view of the UAV. FIG. 3B is aside elevation view of the UAV. FIG. 3C is a top view of the UAV.

FIG. 4A is an isometric view of an UAV that includes a propulsion unitcoupled to the fuselage.

FIG. 4B is an isometric view of an UAV that includes a propulsion unitcoupled to the fuselage and a tail coupled to the fuselage with twobooms.

FIG. 5 is a top view of an UAV that includes pivots located adjacent torotor units.

FIG. 6A is a side elevation view of an UAV, which includes an in-flightreconfigurable wing structure with six rotors, in a horizontal flightconfiguration.

FIG. 6B is a side elevation view of the UAV shown in FIG. 6A, but shownas a hexarotor in the vertical flight configuration.

FIG. 7A is an isometric view of the UAV shown in FIG. 3A with cargocoupled to the UAV via a swing arm. FIG. 7A, shows the swing armpositioning the cargo underneath the fuselage of the UAV during flightin the vertical flight configuration.

FIG. 7B is a side elevation view of the UAV shown in FIG. 7A. FIG. 7B,shows the swing arm positioning the cargo underneath the fuselage of theUAV during flight in the horizontal flight configuration.

FIGS. 8A-8C show an UAV with a swept wing that includes an in-flightreconfigurable wing structure. FIG. 8A shows a top view of the UAV whileFIG. 8B shows a side view. FIG. 8C shows a top view of another UAV wherethe rotors are in a same plane.

FIGS. 9A-9C show yet another UAV with a swept wing that includes anin-flight reconfigurable wing structure and rotor blades adjacent to atrailing edge of the wing structure. FIG. 9A shows a top view of the UAVwhile FIG. 9B shows a side view. FIG. 9C shows a top view of another UAVwhere the rotors are in a same plane.

FIG. 10 is a flow diagram showing an illustrative process to transitionthe in-flight reconfigurable wing structure between a vertical flightconfiguration and a horizontal flight configuration.

FIG. 11 is a block diagram showing an illustrative control system of theUAV described herein.

DETAILED DESCRIPTION

This disclosure is directed to an unmanned aerial vehicle (“UAV”) andsystems, devices, and techniques pertaining to reconfiguring the UAVduring flight to transition between vertical flight and horizontalflight. The UAV may include propulsion units, such as rotors driven byan electric motor, which are coupled to a wing like many conventionalaircraft. However, unlike conventional aircraft, the wing may includeswing segments rotatably coupled together by pivots that rotate toposition the propulsion units around a center of mass of the UAV,typically located within a fuselage, when the UAV's fuselage is orientedperpendicular with the horizon. In this vertical flight configuration,the UAV may operate in a vertical takeoff and landing (VTOL) mode andmay perform vertical flight, hover, and/or perform other flightmaneuvers.

During vertical flight, the UAV may cause a main wing (including bothsides of the wing which are located on opposite sides of a fuselage) toextend outward such that the wing segments become positionedsubstantially parallel to one another and the wing resembles aconventional fixed wing. With the wing extended, the UAV may assume ahorizontal flight configuration. During transition between the verticalflight configuration and the horizontal flight configuration, the UAVmay adjust a pitch or attack angle such that the fuselage becomesoriented substantially parallel to the horizon causing the wing togenerate upward lift while the UAV travels horizontally in thehorizontal flight configuration. In some embodiments, the UAV may beconfigured to land in the horizontal flight configuration using landinggear. In various embodiments, the UAV may reverse the operationsdiscussed above to return the wing to the vertical flight configurationand land in vertical flight configuration.

In some embodiments, the UAV may include a tail that may include controlsurfaces, such as vertical stabilizer with a rudder and/or horizontalstabilizers with elevators. In selected embodiments, the tail may beconfigured to fold (or rotate) toward the fuselage in a stowed positionto enable the UAV to land in the vertical flight configuration. In someembodiments, the tail may fold at least ninety degrees at a pivot nearthe main wing or near the fuselage to reposition the tail and allow forlanding in the vertical flight configuration without damaging the tailby contact with the ground.

In various embodiments, the main wing of the UAV may be a swept wingthat may perform functions of a conventional tail. The swept wing mayextend past the fuselage and include control surfaces such as aileronsand flaps.

The UAV, when flying in the vertical flight configuration, may approachlanding and may land with a fore end of the fuselage pointed toward theground or the sky. In the ground-facing orientation, sensors located inthe fore end of the fuselage may be used to guide landing of the UAV.The rotors may be configured for adjustable pitch from a positive pitchto a negative pitch, thereby reversing a direction of thrust generatedby the rotors (i.e., switching between push and pull). During thetransition between the vertical flight mode and the horizontal flightmode, the pitch of the rotors may be adjusted to reverse the thrustbefore, during, or after the wing is folded/unfolded. Ultimately, theUAV may assume horizontal flight where the fore end of the fuselage ispointed in the direction of travel of the UAV allowing use of thesensors to navigate, detect obstacles, and perform other functions.

In various embodiments, the UAV may be configured to transport a payload(i.e., cargo), from an origination location, such as a fulfillmentcenter, to a destination, such as a delivery destination. The payloadmay be contained within the fuselage. In some embodiments, at least someof the payload may be coupled to the fuselage or the main wing by aswing arm. The swing arm may rotate as the UAV transitions from verticalflight in the vertical flight configuration to horizontal flight in thehorizontal flight configuration. By rotating, the swing arm may positionthe payload underneath the fuselage of the UAV, which may result instable or balanced flight of the UAV and stable transitions between theflight configurations.

The apparatuses, techniques, and systems described herein may beimplemented in a number of ways. Example implementations are providedbelow with reference to the following figures.

FIG. 1 is a pictorial flow diagram showing an illustrative process 100of transitioning between a vertical flight configuration and ahorizontal flight configuration by an unmanned aerial vehicle (UAV) 102.The UAV 102 includes a wing 104 having wing segments that pivot at ornear propulsion units 106 (e.g. rotor units). The wing segments mayenable adjusting the relative location of the propulsion units 106 toreconfigure the UAV 102 during flight between a configuration as a rotorcraft (i.e. vertical flight, hover) to flight as a fixed wing aircraft(i.e., horizontal flight with upward lift from the wing). In FIG. 1,illustrations of the UAV 102(1)-(9) show transition of the UAV 102 fromtakeoff (i.e., the UAV 102(1)) to landing (i.e., the UAV 102(9)), andshowing various stages of flight in-between the takeoff and landing.

At 108, the UAV 102(1) initiates takeoff while in a vertical flightconfiguration 110 where a fuselage of the UAV 102 is orientedperpendicular to the horizon. In a vertical flight configuration 110,the UAV(1) 102 may locate wing segments of the wing 104 to position thepropulsion units 106 around a center of mass of the UAV 102, which maybe located within the fuselage of the UAV 102. In the vertical flightconfiguration 110, a tail 112 of the UAV 102(1) may be folded upwardtoward a front of the fuselage and located in a stowed position. As theUAV 102 begins to rise above the ground in vertical flight, as shown bythe UAV 102(2), the tail 112 may begin to rotate outward from the stowedposition toward an extended position configured to provide lift andcontrol during horizontal flight, such as shown by the UAV 102(5).

At 114, the UAV 102(3) may begin transition to horizontal flight fromvertical flight. To perform the transition, the UAV 102(3) may continueto extend the tail 112 outward to the extended position. The UAV 102(3)may begin to straighten the wing 104 such that the wing segments locatedbetween the propulsion units 106 transition from a non-parallelorientation to a substantially parallel orientation with respect to theother wing segments (shown by the UAV 102(5)). Thus, the wing 104 mayassume a configuration that resembles a main wing on a conventionalfixed-wing aircraft. The UAV 102(4) shows the wing 104 just prior tobeing fully outstretched, and thus just prior to the UAV 104(4)completing the transition to horizontal flight. As the UAV 102(4)transitions to horizontal flight, an attack angle of the UAV 102(4)shifts to position the fuselage closer to parallel to the horizon asshown by the UAV 102(4). Thus, the fuselage of the UAV 102 rotatesninety degrees through the transition from the vertical flight to thehorizontal flight. During the transition, the propulsion units providethe majority of the upward lift to support flight of the UAV 102(3).However, the UAV 102(4) benefits from some lift generated by at least aportion of the wing 104.

At 116, the UAV 102(5) performs horizontal flight while in a horizontalflight configuration 118 where a fuselage of the UAV 102(5) is orientedsubstantially parallel to the horizon. In a horizontal flightconfiguration 118, the UAV 102(5) may generate upward lift from the wing104 while utilizing the propulsion units 106 to generate horizontalthrust. In the horizontal flight configuration 118, the tail 112 may belocated in the extended position configured to provide lift and controlduring horizontal flight. By performing horizontal flight in thehorizontal flight configuration 118, the UAV 102(5) may at leastconserve energy and travel at greater speeds than when flying in thevertical flight configuration 110.

At 120, the UAV 102(6) may begin a transition from horizontal flight inthe horizontal flight configuration 118 to vertical flight in thevertical flight configuration 110. In some embodiments, the UAV 102(6)may initiate an upward angle of attack such that the tail 112 movesbelow the fuselage of the UAV 102(6). The UAV 102(7) may rotate the wingsegments of the wing 104 about the pivots to cause the wing to foldinwards and move toward a location that positions the propulsion units106 around the center of mass of the UAV 102(7). During the transition,the UAV 102(7) may lose upward lift generated by the wing 104 and beginto rely on vertical thrust from the propulsion units 106 to supportflight of the UAV 102(7).

At 122, the UAV 102(8) may stow the tail 112 in the stowed position andmay assume flight by reliance on the propulsion units 106 providingvertical thrust to support flight of the UAV 102(8). The UAV 102(9) mayland on landing features while the tail is stowed in the stowed positionand the wing segments position the propulsion units 106 around thecenter of mass of the UAV 102(9).

FIG. 2A is an isometric view of the UAV 102 shown in the horizontalflight configuration 118, and thus represented as the UAV 102(5)discussed above with reference to FIG. 1. As shown in FIG. 2A, the UAV102 includes four propulsion units 106 coupled to the wing 104. However,the UAV 102 may include more or fewer propulsion units 104. At leastsome of the propulsion units 104 may be coupled to the UAV 102 somewhereother than the wing 104, such as on a fuselage 202 of the UAV 102. Thepropulsion units 106 may be implemented using rotors, jet engines, turbofans, and/or other types of thrust generating mechanisms.

The propulsion units may be powered by electricity (e.g., batterypower), combustion of material (e.g., gas, solid fuel), and/or chemicalreaction, which may be used separately or in combination. When thepropulsion units 106 include rotors 204 (as shown in FIG. 2A), therotors may be rotated by electric motors. The rotors 204 may includefixed or variable pitch rotor blades. Variable pitch blades enableadjustment of the pitch of the rotor blades to increase or decrease anamount of air moved by the rotor blades (and thus the resultant thrust)during a rotation of the rotor. The variable pitch may also beconfigured to allow transition between a positive pitch and a negativepitch, which may reverse a direction of resultant thrust caused byrotation of the rotor.

The wing 104 may include various wing segments 206 that span at leastpartly between the propulsion units 104 and position the propulsionunits 104 in different locations based on different configurationsassumed by the wing segments 206. The wing segments 206 may include afirst wing segment 206(1), a second wing segment 206(2), and a thirdwing segment 206(3) when the UAV 102 includes four propulsion units 106.However, the wing 104 may include more or fewer of the wing segments 206in some embodiments. Each of the wing segments 206 may rotatably coupleto another one of the wing segments 206 via pivots 208 that causerotation about a respective axis 210. As shown in FIG. 2A, the UAV 102may include a first pivot 208(1) that rotatably couples the first wingsegment 206(1) to the second wing segment 206(2) to enable rotationabout a first axis 210(1). Similarly, a second pivot 208(2) mayrotatably couple the second wing segment 206(2) to the third wingsegment 206(3) to enable rotation about a second axis 210(2). The secondwing segment 206(2) may be fixed with respect to fuselage 202 by afuselage support structure 212. In some embodiments, each of the pivots208 may be located adjacent to one of the propulsion units 104. However,the pivots may also be collinear to respective propulsion units such aswhen the propulsion unit in included within a hinge configuration thatforms the pivot. For example, the propulsion unit may act like a pinwithin a hinge configuration that enables rotation of the hingeconfiguration.

The UAV 102 may include various sensors to monitor various aspects ofcontrol of the UAV. The sensors may include many of the same sensorsused on conventional aircraft, drones, or unmanned aerial vehicles(UAVs). At least one sensor 214 may be located proximate to a fore endof the fuselage. The sensor 214 may include an image sensor to providevisual information to assist flight of the UAV.

The tail 112 and the wing 104 may include control surfaces, such asflaps, ailerons, and/or stabilizers to stabilize and enable control ofthe UAV 102 during flight in the horizontal flight configuration wherethe UAV 102 relies on upward lift generated by the wing 104. The tail112 may include one or more tail booms 216 that secure the tail 112 tothe wing 104 and/or to the fuselage 202 via a rotatable tail pivot 218.The rotatable tail pivot 218 enables rotation of the tail with respectto the wing 104. Using the rotatable tail pivot, the tail may be rotatedfrom/to a stowed position after takeoff and just prior to landing,respectively, as discussed above with reference to the process 100. Thetail 112 may include a horizontal stabilizer 220 and a verticalstabilizer 222.

The UAV 102 has a center of mass that may be located within the fuselage202 or proximate to the fuselage 202. In some embodiments, the UAV 102may be configured to carry a payload, which may be carried within thefuselage 202 or may be coupled to the fuselage 202. For example, thepayload may be coupled to the fuselage 202 or the wing 104 via a swingarm, which is discussed in further detail below. The addition of thepayload may modify a location of the center of mass of the UAV 102.

FIG. 2B is a side elevation view of the UAV shown in the horizontalflight configuration 118. FIG. 2C is a top view of the UAV shown in thehorizontal flight configuration 118.

FIG. 3A is an isometric view of the UAV 102 shown in the vertical flightconfiguration 110, and thus represented as, for example, the UAV 102(8)discussed above with reference to FIG. 1. As shown in FIG. 3A, theorientation of the fuselage 202 is perpendicular to the horizon andapproximately ninety degrees different than the orientation of thefuselage 202 shown in FIG. 2A, which is shown as being parallel to thehorizon in FIG. 2A. As discussed above, the UAV 102 may rotate the wingsegments 206 relative to an axis to position the propulsion units 106around a center of mass of the UAV 102. The center of mass may belocated within the fuselage or proximate to the fuselage 202, such aswhen a payload (or cargo) is coupled to the fuselage 202. To transitionfrom the horizontal flight configuration 118 shown in FIG. 2A to thevertical flight configuration 110 shown in FIG. 3A, pivot drivemechanisms may cause the wing segments 206 to rotate approximately anangle α 302, via the pivots 208, about respective axes 210. The pivotdrive mechanisms may include at least one of servos, linear actuators,electric motors, cable pulleys, and/or other mechanisms to causerotation of a first wing segment relative to a second, adjacent wingsegment. The pivot drive mechanism may be coupled to the pivot, to theadjacent wing sections near the pivot, or both the pivot and theadjacent wing sections. In some embodiments, biasing devices (e.g., coilsprings, leaf springs, etc.) may cause the wing segment to assume afirst configuration (e.g., the horizontal flight configuration or thevertical flight configuration) while the pivot drive mechanisms maycause the wings to transition to a second, different configuration(e.g., the vertical flight configuration or the horizontal flightconfiguration). Locking devices and/or friction devices may be used tomaintain a current configuration during flight (e.g., mechanical lock,magnetic lock, electronic lock, etc.). The locking mechanisms may beincluded in the pivots, the pivot drive mechanisms, or in otherstructures as discussed herein. These devices may be used to stiffenand/or stabilize components. In some embodiments, the pivot drivemechanisms may lock the wings in a configuration.

FIG. 3B is a side elevation view of the UAV 102 shown in the verticalflight configuration 110. The side elevation view of FIG. 3B is definedwith respect to the view shown in FIG. 2A. However, when the UAV 102 isin flight in the vertical flight configuration 110, the view shown inFIG. 3B appears as a top view.

FIG. 3C is a top view of the UAV 102 shown in the vertical flightconfiguration 110. The top view of FIG. 3C is defined with respect tothe view shown in FIG. 2A. However, when the UAV 102 is in flight in thevertical flight configuration 110, the view shown in FIG. 3C appears asa side elevation view.

The above discussion of the UAV 102 provides a general description ofembodiments of the UAV 102 and various configurations. The followingdiscussion and associated figures include various embodiments and/orversions of the UAV 102 or other UAVs that rely on the principlesdiscussed above. Embodiments and features of the UAV discussed hereinmay be combined with other embodiments and/or other features of the UAVdiscussed herein to create a version of the UAV possibly not explicitlyshown in the figures, but disclosed herein nonetheless.

FIG. 4A is an isometric view of an UAV 400. The UAV 400 is shown in thevertical flight configuration 110 and is similar or the same as the UAV102 shown in FIG. 3A except possibly as described below in this section.

The UAV 400 includes at least one propulsion unit 402 coupled to afuselage 404. The propulsion unit 402 may be a rotor unit that includesa rotor similar to or the same as the rotor 204 discussed above. Whilethe propulsion unit 402 is shown proximate to a fore end 406 of thefuselage 404, the propulsion unit 402 may be coupled proximate to an aftend 408 of the fuselage 404 or multiple propulsion units may be coupledto the fuselage 404 proximate to the fore end 406, the aft end 408, orboth. The sensor 214 may be located on the fuselage support structure212 to accommodate the propulsion unit 402 being coupled to the fuselage402.

The UAV 400 includes the tail 112. The tail may be configured to pivotinwards toward the aft end 408 of the fuselage 404. To cause the tailboom 216 to avoid interfering with or contact with the fuselage 404, therotatable tail pivot 218 may be rotated about an axis that is notparallel with the wing 104 or the tail boom 216 may include multiplebooms with a gap there between to avoid interference with or contactwith the fuselage when the tail boom(s) are folded in the stowedposition as shown in FIG. 4A.

FIG. 4B is an isometric view of the UAV 400, but including a tailcoupled to the fuselage with two tail booms 410. The two tail booms 410may include a gap between the booms to accommodate the fuselage 202, andthus to avoid interference with or contact with the fuselage 202 whenthe tail booms are folded in the stowed position as shown in FIG. 4B.

FIG. 5 is a top view of an UAV 500. The UAV 500 is shown in thehorizontal flight configuration 118 and is similar or the same as theUAV 102 shown in FIG. 2C except possibly as described below in thissection.

The UAV 500 may include the pivots 208 that cause the wing segments 206to rotate about respective axes 210. The pivots 208 may be locatedadjacent to at least one of the propulsion units 106. For example, thewing segment 206(2) may include two propulsion units 106(2) and 106(3)within the wing segment 206(2). The wing segment 206(2) may include awing portion 502 on either side of the propulsion units 106(2) and106(3), which extend outward (from the perspective of the fuselagesupport structure 212) and couple to the pivots 208. Thus, a rotationalaxis of the rotor 204(3) is different than the rotational axis of thepivot 208(1). In some embodiments, the one of the pivots 208 may belocated between the propulsion unit 106(2) and the fuselage supportstructure 212 while the other one of the pivots 208 may be locatedbetween the propulsion unit 106(3) and the fuselage support structure212. In these embodiments, the wing segment 206(1) may couple thepropulsion units 106(1) and 106(2) while the wing segment 206(3) maycouple the propulsion units 106(3) and 106(4).

The UAV 500 may include rotors 504 located proximate to a trailing edge506 of the wing 104 in addition to or instead of the rotors 204 locatedproximate to a leading edge 508 of the wing 104. Use of the rotors 504may enable landing in a position to orient the fore end 406 of thefuselage toward the ground, such as toward a landing zone, therebyenabling use of the sensor 214 located on the fore end of the fuselage202.

FIG. 6A is a side elevation view of an UAV 600. The UAV 600 is shown inthe horizontal flight configuration 118 and is similar or the same asthe UAV 102 shown in FIG. 3A except possibly as described below in thissection.

The UAV 600 may include six propulsion units 602 (or possibly morepropulsion units). In some embodiments, the UAV 600 may be configuredsuch that the wing 104, when in the horizontal flight configuration 118,maintains a small angle β 604 between the various wing segments 206.However, the wing 104 may still orient the wing segments substantiallyparallel to one another where the adjacent wing surfaces include andeviation of the small angle β 604 of plus/minus five degrees fromparallel when in the horizontal flight configuration. The wing, when inthe horizontal flight configuration, may be fixed or locked in place tomaintain a consistent angle between adjacent wing segments.

In some embodiments, the fuselage 202 of the UAV 600 may include wingsupport arms 606 that extend outward from the fuselage 202 and are usedto support the wings when the UAV 600 is in the vertical flightconfiguration 110, shown in FIG. 6B. The support arms 606 may couple torespective wing coupling features 608 to at least partially restrictmovement of the wings, as discussed below. Other locking mechanisms maybe employed in the pivots and/or in other locations to maintain aconfiguration of the wing 104 and/or stiffen the wing 104 while the UAV600 is in the horizontal flight configuration 118 and/or the verticalflight configuration 110. As discussed above, this feature, and allothers discussed herein may be employed in some embodiments on the UAV102 discussed above.

In accordance with some embodiments, the support arms 606 may be coupledto the coupling features 608 by winding a cable 610. For example, thecable 610 may be fixed at one end (e.g., at the coupling features 608)and wrapped around a spool on a second end (e.g., at the support arms606). Rotation of the spool may cause the cable 610 to be wound, and betaken in, thereby causing the wings to fold toward the fuselage 202 asshown in FIG. 6B.

In various embodiments, a stiffening cable assembly 612 may beconfigured within the wing 104. The stiffening cable assembly 612 may beconfigured to stiffen the wing 104 in the horizontal position when thestiffening cable assembly 612 is in tension. The stiffening cableassembly 612 may include a spool that winds the cable to cause the cableto be in tension, and thus cause the stiffening of the wing 104. Thestiffening cable assembly 612 may be used to cause the wings to foldaway the fuselage 202 as shown in FIG. 6A. The support arms 606,coupling features 608, and/or the stiffening cable assembly 612 may beincluded in any of the embodiments disclosed herein, and are not limitedto the UAV 600.

FIG. 6B shows a side elevation view of the UAV 600 shown in FIG. 6A, butshown as a substantially symmetrical parallelogram (e.g., a hexarotor asa hexagon) in the vertical flight configuration 110. The side elevationview of FIG. 6B is defined with respect to the view shown in FIG. 6A.However, when in flight in the vertical flight configuration 110, theview shown in FIG. 3B appears as a top view. To transition from thehorizontal flight configuration 118 shown in FIG. 6A to the verticalflight configuration 110 shown in FIG. 6B, pivot drive mechanisms maycause the wing segments to rotate an angle δ 614, via the pivots, aboutrespective axes. In some embodiments, the wing segments may flex tocause the shape shown in FIG. 6B, which may or may not include use ofthe pivots. Thus, the wing may flex and enable bending withoutdeformation to translate between the horizontal flight configuration 118shown in FIG. 6A and the vertical flight configuration 110 shown in FIG.6B.

As shown in FIG. 6B, the support arms 606 may be coupled tocorresponding ones of the wing coupling features 608 to at leastpartially secure the wing segments 206 in the vertical flightconfiguration 110. The coupling may be performed by a mechanicalcoupling, an electrical coupling, and/or a magnetic coupling.

FIG. 7A is an isometric view of the UAV 102 shown in FIG. 3A with cargo702 coupled to the UAV 102 via a swing arm 704. FIG. 7A, shows the swingarm 704 positioning the cargo 702 underneath the fuselage 202 of the UAV102 during flight in the vertical flight configuration 110. As discussedherein, the cargo 702 includes items for delivery or transport by theUAV 102 including a container or container(s) used to transport suchitems. The term “cargo” 702 is used interchangeable herein with the term“payload.” In some embodiments, the cargo 702 may be formed as a liftingbody, which may generate lift while the UAV is in horizontal flight. Thecargo 702 may be formed of an aerodynamic shape/profile to reduce dragwhile still having large or maximized space for transport of items.

The swing arm 704 may be rotatably coupled to a swing arm pivot 706 thatallows the swing arm to rotate about an axis associated with the swingarm pivot 706. By allowing the swing arm to rotate, the center of massof the UAV 102 when coupled to the cargo 702 may be positioned near orbelow the center of mass of the UAV 102 (when the cargo 702 is notcoupled to the UAV 102). More specifically, as shown in FIG. 7A, thecenter of mass of the UAV 102 with the cargo 702 may be approximatelyequidistant from each of the rotors 204, thereby sharing the load of thecargo 702 between each rotor.

FIG. 7B is a side elevation view of the UAV 102 shown in FIG. 7A. FIG.7B, shows the swing arm positioning the cargo underneath the fuselage202 of the UAV during flight in the horizontal flight configuration 118.

FIG. 8A shows a top view of an UAV 800 shown in the horizontal flightconfiguration 118 and is similar or the same as the UAV 102 shown inFIG. 3A except possibly as described below in this section.

The UAV 800 includes a swept wing 802 that is configurable to transitionbetween the horizontal flight configuration 118 (shown in FIG. 8A) and avertical flight configuration. The swept wing 802 may include rotorsproximate to a leading edge of the swept wing 802 and control surfaceson a trailing edge of the swept wing 802 to enable the UAV 800 tomaintain horizontal flight using lift generated by the swept wing 802.The UAV 800 may include a wing tip 804 that extends outward (from aprospective of the fuselage 202) past the propulsion units. FIG. 8Bshows a side view of the UAV 800. As shown in FIGS. 8A and 8B, therotors 204(1) and 204(4) are aligned in a first plane while rotors204(2) and 204(3) are aligned in a second, different plane. FIG. 8Cshows a top view of an UAV 806 that is similar to the UAV 800 butincludes all of the rotors 204 aligned in a same plane.

FIG. 9A shows a top view of an UAV 900 shown in the horizontal flightconfiguration 118 and is similar or the same as the UAV 102 shown inFIG. 3A except possibly as described below in this section. The UAV 900includes a swept wing 802 that is configurable to transition between thehorizontal flight configuration 118 (shown in FIG. 9A) and a verticalflight configuration. The swept wing 802 may include rotors proximate toa trailing edge of the swept wing 802 and control surfaces on thetrailing edge of the swept wing 802 to enable the UAV 900 to maintainhorizontal flight using lift generated by the swept wing 802. FIG. 9Bshows a side view of the UAV 900. As shown in FIGS. 9A and 9B, therotors 204(1) and 204(4) are aligned in a first plane while rotors204(2) and 204(3) are aligned in a second, different plane. FIG. 9Cshows a top view of an UAV 902 that is similar to the UAV 900 butincludes all of the rotors 204 aligned in a same plane.

FIG. 10 is a flow diagram showing an illustrative process 1000 totransition the in-flight reconfigurable wing structure between thevertical flight configuration and the horizontal flight configuration.The process 1000 is illustrated as a collection of blocks in a logicalflow graph, which represent a sequence of operations. The order in whichthe operations are described is not intended to be construed as alimitation, and any number of the described blocks can be combined inany order and/or in parallel to implement the process 1000.

At 1002 the UAV 102 may be configured in the vertical flightconfiguration 110 shown in FIG. 3A. The wing segments may position therotors units around the center of mass of the UAV 102. The UAV 102 maypower up rotors by supplying power to electric motors coupled to therotors. The rotors may generate downward thrust to lift the UAV 102 offof the ground. The UAV 102 may lift off of the ground and assumevertical flight as a rotor craft. In some embodiments, the UAV 102 maytakeoff with the fore end of the fuselage 202 pointed downward. Thisorientation may be ideal in some instances to enable the sensor 214 tobe used during landing to identify a landing zone, and so forth. In someembodiments, the UAV 102 may be rotated prior to takeoff to orient thefore end of the fuselage 202 upwards toward the sky and away from theground.

At 1004, the UAV 102 may rotate a tail from a stowed position to anextended position when the tail is configured to be stowed for takeoffand landing. However, when the UAV 102 includes a swept wing design, theoperation 1004 (and similar operations) may not be preformed.

At 1006, after the UAV 102 has flown to at least a predetermineddistance above the ground level, a pitch of rotor blades of the UAV 102may be adjusted to reverse a direction of thrust produced by the rotors.For example, when the UAV 102 takes off with the fore end of thefuselage 202 pointed downward, the UAV 102 may require thrust in a firstdirection for takeoff and vertical flight in the vertical flightconfiguration and thrust in a second, opposite direction (relative tothe propulsion unit) to assume horizontal flight in the horizontalflight configuration. Thus, the UAV 102 may adjust a pitch of the rotorblades between a positive pitch and a negative pitch to reverse thethrust produced by the rotors. During the reverse of the thrust, the UAV102 may rely on current momentum to maintain flight.

At 1008, the UAV 102 may unfold/extend the wings such that the wingsegments become aligned substantially parallel to one another, therebytransforming the wing into a conventional fixed wing configuration.

At 1010, the UAV 102 may assume horizontal flight in the horizontalflight configuration 118 shown in FIG. 2A, where the fore end of thefuselage 202 is directed in the direction of travel. By travelinghorizontally in the horizontal flight configuration 118, the UAV 102 mayconserve energy and reach greater speed as compared to horizontal flightin the vertical flight configuration 110.

At 1012, typically when the UAV 102 has approached or is near a landingzone, the UAV may transition to the vertical flight configuration 110and land using vertical flight. However, in some embodiments, the UAV102 may land in the horizontal flight configuration 118, such as inemergency situations, when UAV 102 is equipped with landing gear (e.g.,wheeled landing gear, skis, reinforced hull/fuselage, pontoons, etc.),and/or possibly in other situations. To begin the transition to thevertical flight configuration 110, at 1012, the UAV 102 may increase anangle of attack upwards to increase the pitch of the UAV 102.

At 1014, the UAV 102 may begin to fold the wings to assume the verticalflight configuration 110 shown in FIG. 3A.

At 1016, before the UAV 102 drops below a predetermined distance abovethe ground level, a pitch of rotor blades of the UAV 102 may be adjustedto reverse a direction of thrust produced by the rotors. For example,when the UAV 102 is to land with the fore end of the fuselage 202pointed downward, the UAV may require thrust in a first direction toassume flight in the horizontal flight configuration and thrust in asecond, opposite direction (relative to the propulsion unit) for flightand landing in the vertical flight configuration. Thus, the UAV 102 mayadjust a pitch of the rotor blades between a positive pitch and anegative pitch to reverse the thrust produced by the rotors. During thereverse of the thrust, the UAV 102 may rely on current momentum tomaintain flight.

At 1018, the UAV 102 may perform vertical flight in the vertical flightconfiguration. At 1018, the UAV 102 may fold or stow the tail byrotating the tail from the extended position to the stowed position whenthe UAV 102 includes the tail. However, when the UAV 102 includes aswept wing design, the operation 1018 may not be preformed.

At 1020, the UAV 102 may land in the vertical flight configuration anddiscontinue vertical flight by powering down electric motors that drivethe rotors.

When the UAV 102 is configured with the cargo using the swing arm, theUAV 102 may release cargo while performing flight in the horizontalflight configuration at the operation 1010. Landing gear and/or aspecial takeoff/landing zone may accommodate clearances to enable use ofthe swing arm and cargo by the UAV 102.

FIG. 11 is a block diagram showing an illustrative control system 1100that may be used to implement at least some of the techniques discussedabove. In the illustrated implementation, the UAV control system 1100includes one or more processors 1102, coupled to a non-transitorycomputer readable storage medium 1122 via an input/output (I/O)interface 1110. The UAV control system 1100 may also include a rotormotor controller 1104, power supply module 1106 and/or a navigationsystem 1108. The UAV control system 1100 further includes an inventory(cargo) engagement mechanism controller 1112, a wing configurationcontroller 1114, a network interface 1118, and one or more input/outputdevices 1120.

In various implementations, the UAV control system 1100 may be auniprocessor system including one processor 1102, or a multiprocessorsystem including several processors 1102 (e.g., two, four, eight, oranother suitable number). The processor(s) 1102 may be any suitableprocessor capable of executing instructions. For example, in variousimplementations, the processor(s) 1102 may be general-purpose orembedded processors implementing any of a variety of instruction setarchitectures (ISAs), such as the x86, PowerPC, SPARC, or MIPS ISAs, orany other suitable ISA. In multiprocessor systems, each processor(s)1102 may commonly, but not necessarily, implement the same ISA.

The non-transitory computer readable storage medium 1122 may beconfigured to store executable instructions, data, flight paths and/ordata items accessible by the processor(s) 1102. In variousimplementations, the non-transitory computer readable storage medium1122 may be implemented using any suitable memory technology, such asstatic random access memory (SRAM), synchronous dynamic RAM (SDRAM),nonvolatile/Flash-type memory, or any other type of memory. In theillustrated implementation, program instructions and data implementingdesired functions, such as those described above, are shown storedwithin the non-transitory computer readable storage medium 1122 asprogram instructions 1124, data storage 1126 and flight path data 1128,respectively. In other implementations, program instructions, dataand/or flight paths may be received, sent or stored upon different typesof computer-accessible media, such as non-transitory media, or onsimilar media separate from the non-transitory computer readable storagemedium 1122 or the UAV control system 1100. Generally speaking, anon-transitory, computer readable storage medium may include storagemedia or memory media such as flash memory (e.g., solid state memory),magnetic or optical media (e.g., disk) coupled to the UAV control system1100 via the I/O interface 1110. Program instructions and data storedvia a non-transitory computer readable medium may be transmitted bytransmission media or signals such as electrical, electromagnetic, ordigital signals, which may be conveyed via a communication medium suchas a network and/or a wireless link, such as may be implemented via thenetwork interface 1118.

In one implementation, the I/O interface 1110 may be configured tocoordinate I/O traffic between the processor(s) 1102, the non-transitorycomputer readable storage medium 1122, and any peripheral devices, thenetwork interface or other peripheral interfaces, such as input/outputdevices 1120. In some implementations, the I/O interface 1110 mayperform any necessary protocol, timing or other data transformations toconvert data signals from one component (e.g., non-transitory computerreadable storage medium 1122) into a format suitable for use by anothercomponent (e.g., processor(s) 1102). In some implementations, the I/Ointerface 1110 may include support for devices attached through varioustypes of peripheral buses, such as a variant of the Peripheral ComponentInterconnect (PCI) bus standard or the Universal Serial Bus (USB)standard, for example. In some implementations, the function of the I/Ointerface 1110 may be split into two or more separate components, suchas a north bridge and a south bridge, for example. Also, in someimplementations, some or all of the functionality of the I/O interface1110, such as an interface to the non-transitory computer readablestorage medium 1122, may be incorporated directly into the processor(s)1102.

The rotor motor(s) controller 1104 communicates with the navigationsystem 1108 and adjusts the power of each rotor motor to guide the UAValong a determined flight path. In some embodiments, where the rotorblades are configured for variable pitch, the rotor motor(s) controller1104 may adjust the pitch of the rotor blades. The power supply module1106 may control the charging and any switching functions associatedwith one or more power modules (e.g., batteries) of the UAV, such as thepower sources 614, 714.

The navigation system 1108 may include a GPS or other similar systemthat may be used to navigate the UAV to and/or from a location. Theinventory engagement mechanism controller 1112 communicates with theactuator(s) or motor(s) (e.g., a servo motor) used to engage and/ordisengage inventory. For example, when the UAV is positioned over alevel surface at a delivery location, the inventory engagement mechanismcontroller 1112 may provide an instruction to a motor that controls theinventory engagement mechanism to release the inventory.

The wing configuration controller 1114 may control one or more pivotdrive mechanisms 1116 to cause the wings to maintain the vertical flightconfiguration 112 or the horizontal flight configuration 118 (possiblyby engaging/disengaging locks or friction mechanisms) and/or totransition between the vertical flight configuration 112 or thehorizontal flight configuration 118. For example, the wing configurationcontroller 1114 may cause servos or rotational motors to cause wingsegments to rotate about a pivot as discussed herein. In someembodiments, the pivot drive mechanisms 1116 may include the propulsionunit or rotor motor and controllable by the wing configurationcontroller 1114, possibly using an engagement mechanism or gear thatcauses the power transmission to rotate the wing segments.

The network interface 1118 may be configured to allow data to beexchanged between the UAV control system 1100, other devices attached toa network, such as other computer systems, and/or with UAV controlsystems of other UAVs. For example, the network interface 1118 mayenable wireless communication between numerous UAVs. In variousimplementations, the network interface 1118 may support communicationvia wireless general data networks, such as a Wi-Fi network. Forexample, the network interface 1118 may support communication viatelecommunications networks such as cellular communication networks,satellite networks, and the like.

Input/output devices 1120 may, in some implementations, include one ormore displays, image capture devices, thermal sensors, infrared sensors,time of flight sensors, accelerometers, pressure sensors, weathersensors, airflow sensors, etc. Multiple input/output devices 1120 may bepresent and controlled by the UAV control system 1100. One or more ofthese sensors may be utilized to assist in landings as well as avoidingobstacles during flight.

As shown in FIG. 11, the memory may include program instructions 1124which may be configured to implement the example processes and/orsub-processes described above. The data storage 1126 may include variousdata stores for maintaining data items that may be provided fordetermining flight paths, retrieving inventory, landing, identifying alevel surface for disengaging inventory, causing movement of ballast,etc.

In various implementations, the parameter values and other dataillustrated herein as being included in one or more data stores may becombined with other information not described or may be partitioneddifferently into more, fewer, or different data structures. In someimplementations, data stores may be physically located in one memory ormay be distributed among two or more memories.

Those skilled in the art will appreciate that the UAV control system1100 is merely illustrative and is not intended to limit the scope ofthe present disclosure. In particular, the computing system and devicesmay include any combination of hardware or software that can perform theindicated functions, including computers, network devices, internetappliances, PDAs, wireless phones, pagers, etc. The UAV control system1100 may also be connected to other devices that are not illustrated, orinstead may operate as a stand-alone system. In addition, thefunctionality provided by the illustrated components may in someimplementations be combined in fewer components or distributed inadditional components. Similarly, in some implementations, thefunctionality of some of the illustrated components may not be providedand/or other additional functionality may be available.

Those skilled in the art will also appreciate that, while various itemsare illustrated as being stored in memory or storage while being used,these items or portions of them may be transferred between memory andother storage devices for purposes of memory management and dataintegrity. Alternatively, in other implementations, some or all of thesoftware components may execute in memory on another device andcommunicate with the illustrated UAV control system 1100. Some or all ofthe system components or data structures may also be stored (e.g., asinstructions or structured data) on a non-transitory,computer-accessible medium or a portable article to be read by anappropriate drive, various examples of which are described above. Insome implementations, instructions stored on a computer-accessiblemedium separate from the UAV control system 1100 may be transmitted tothe UAV control system 1100 via transmission media or signals such aselectrical, electromagnetic, or digital signals, conveyed via acommunication medium such as a wireless link. Various implementationsmay further include receiving, sending or storing instructions and/ordata implemented in accordance with the foregoing description upon acomputer-accessible medium. Accordingly, the techniques described hereinmay be practiced with other UAV control system configurations.

CONCLUSION

Although the subject matter has been described in language specific tostructural features and/or methodological acts, it is to be understoodthat the subject matter defined in the appended claims is notnecessarily limited to the specific features or acts described. Rather,the specific features and acts are disclosed as illustrative forms ofimplementing the claims.

What is claimed is:
 1. An unmanned aerial vehicle (UAV) comprising: afuselage configured to transport cargo that is coupled to the fuselageor stored within the fuselage; a plurality of propulsion units to causepropulsion of the UAV; a main wing coupled to the fuselage, the mainwing having a plurality of wing segments, each wing segment spanningbetween two different ones of the plurality of propulsion units, themain wing including: coupling features to couple each of the pluralityof propulsion units; a plurality of pivots, each pivot located betweenadjacent wing segments, the plurality of pivots configured to modify ashape of the wing between (i) a horizontal flight configuration wherethe plurality of wing segments are oriented approximately parallel toone another and (ii) a vertical flight configuration where the pluralityof wing segments symmetrically orient the plurality of propulsion unitsaround the fuselage; and a drive mechanism to cause the plurality wingsegments to rotate about the plurality of pivots during flight totransition between the horizontal flight configuration and the verticalflight configuration; a power source coupled to the fuselage toselectively provide power to the plurality propulsion units and thedrive mechanism; and a control system coupled to the fuselage and incommunication with at least the plurality of propulsion units, the drivemechanism, and the power source, the control system to control at leastoperation of the plurality of propulsion units and a transition of themain wing between the horizontal flight configuration and the verticalflight configuration, wherein the UAV is configured to (i) sustainhorizontal flight in the horizontal flight configuration while thefuselage is oriented parallel to a horizon and (ii) sustain verticalflight in the vertical flight configuration while the fuselage isoriented perpendicular with the horizon.
 2. The UAV as recited in claim1, further comprising a tail that extends outward from the fuselage andincludes control surfaces for use during the horizontal flight in thehorizontal flight configuration, the tail configured to rotate about apivot to transition the tail from an extended position used in thehorizontal flight configuration to a stowed position during verticalflight in the vertical flight configuration.
 3. The UAV as recited inclaim 1, wherein the main wing is a swept wing that includes controlsurfaces on a trailing edge that extends behind an aft end of thefuselage.
 4. The UAV as recited in claim 1, further comprising: at leasttwo wing support arms that couple to respective coupling featureslocated on the main wing when the UAV is in the vertical flightconfiguration, each wing support arm to stabilize a wing segment whencoupled to a respective coupling feature; and a stiffening cableassembly coupled to the wing assembly, the stiffening cable assemblyconfigured to stiffen the wing assembly in the horizontal flightconfiguration when the stiffening cable assembly is in tension.
 5. Anaerial vehicle comprising: a fuselage; a plurality of propulsion units;and a wing assembly comprising a plurality of wing segments, whereineach of the plurality of wing segments is connected to an adjacent wingsegment through a respective pivot, wherein each pivot defines a pivotaxis between an intersection of the respective pivot with a leading edgeand a trailing edge of the wing assembly, wherein the plurality of wingsegments are configured to rotate around the pivot axis during flightbetween (i) a horizontal flight configuration where the plurality ofwing segments are oriented approximately parallel to one another and(ii) a vertical flight configuration where the plurality of wingsegments are positioned around the fuselage, wherein one of theplurality of propulsion units is located proximate to and substantiallyparallel with each pivot axis.
 6. The aerial vehicle as recited in claim5, further comprising a swing arm rotatably coupled to the fuselage, theswing arm to selectively couple to cargo, the swing arm to position thecargo in a first position under the fuselage when the aerial vehicle isin the vertical flight configuration and in a second, different positionunder the fuselage when the aerial vehicle is in the horizontal flightconfiguration.
 7. The aerial vehicle as recited in claim 5, furthercomprising a tail that extends outward from the fuselage and includescontrol surfaces for use during horizontal flight in the horizontalflight configuration, the tail configured to rotate about a tail pivotto transition the tail from an extended position used in the horizontalflight configuration to a stowed position used in the vertical flightconfiguration.
 8. The aerial vehicle as recited in claim 5, wherein afore end of the fuselage further comprises at least one imaging sensorused to assist in navigation of the aerial vehicle.
 9. The aerialvehicle as recited in claim 5, wherein the wing assembly comprises threewing segments and two pivots.
 10. The aerial vehicle as recited in claim5, wherein one of the plurality of propulsion units is located proximateto opposite ends of each wing segment.
 11. The aerial vehicle as recitedin claim 5, wherein the wing assembly further comprises locking arms tostiffen the wing assembly in the horizontal flight configuration. 12.The aerial vehicle as recited in claim 5, wherein at least one of thewings segments comprises a swept-wing shape.
 13. The aerial vehicle asrecited in claim 5, further comprising at least two wing support armsthat couple to respective coupling features located on the wing assemblywhen the aerial vehicle is in the vertical flight configuration, eachsupport arm of the at least two wing support arms to stabilize a wingsegment when coupled to a respective coupling feature.
 14. The aerialvehicle as recited in claim 5, further comprising a drive mechanismconfigured to rotate the plurality of wing segments about each pivot.15. The aerial vehicle as recited in claim 5, wherein the drivemechanism comprises at least one of a servo, a linear actuator, and anelectric motor.
 16. An aerial vehicle comprising: a plurality ofpropulsion units; a wing assembly having a plurality of wing segmentscoupled to at least one propulsion unit of the plurality of propulsionunits and coupled to at least one of a plurality of pivots, each wingsegment spanning between two different ones of the plurality ofpropulsion units, each wing segment rotatably coupled to at least oneother wing segment by a pivot of the plurality of pivots that areconfigured to modify a shape of the wing assembly during flight between(i) a horizontal flight configuration where the plurality of wingsegments are oriented approximately parallel to one another and (ii) avertical flight configuration where the plurality of wing segmentsposition the plurality of propulsion units to form a substantiallysymmetrical parallelogram; and a drive mechanism to cause the pluralityof wing segments to rotate about the plurality of pivots to transitionthe shape of the wing assembly between the horizontal flightconfiguration and the vertical flight configuration.
 17. The aerialvehicle as recited in claim 16, wherein the aerial vehicle is configuredto (i) sustain horizontal flight in the horizontal flight configurationwhile the wing assembly is oriented parallel to a horizon and (ii)sustain vertical flight in the vertical flight configuration while thewing assembly is oriented perpendicular with the horizon.
 18. The aerialvehicle as recited in claim 16, wherein at least one of the plurality ofwing segments comprises a swept-wing shape.
 19. The aerial vehicle asrecited in claim 16, wherein the plurality of pivots are located atlocations on the wing assembly that are different than locations of theplurality of propulsion units.
 20. The aerial vehicle as recited inclaim 16, wherein the propulsion units are rotor units, each rotor unitincluding an electric motor to rotate at least one rotor to generatethrust to cause propulsion of the UAV, and wherein the at least onerotor is configured for variable pitch, the variable pitch configured toreverse a direction of the thrust.